jbm@eos.arc.nasa.gov (Jeffrey Mulligan) (11/28/90)
ph@miro.Berkeley.EDU (Paul Heckbert) writes: >Related question: is there a formula relating camera lens >focal length and angle of view? (I would guess that such a relationship >would not be theoretical, but would be based on praticalities, >and would vary from manufacturer to manufacturer) Focal length and angular field are independent. For example, you can have a 50mm focal length lens which is a "standard" lens for 35mm photography, or a 50mm wide angle lens for a larger film format. There are some applications (enlarging?) where it is sometimes recommended to use a wide angle lens from a larger film format in place of a standard lens to assure better field uniformity. For a family of lenses designed for a given film size, then of course there will be a relationship between focal length and field of view, since economics dictate that the field of view should be no larger than necessary. Note that the field does not have a sharply defined size, but that the intensity drops off continuously at the margins of the field (vignetting). -- Jeff Mulligan (jbm@eos.arc.nasa.gov) NASA/Ames Research Ctr., Mail Stop 262-2, Moffett Field CA, 94035 (415) 604-3745